#include<stdio.h>
#include<stdlib.h>
#include<string.h>

//char my_str2[] = "Hello";
byte message = 240;

void setup() {
  
  //C语言数字转数组
  char a[5];
  sprintf(a, "%d", message);
  Serial.begin(9600);
  Serial.println(a);
  message ++;
}

void loop() {
  // put your main code here, to run repeatedly:
//  setup();
  delay(1000);
}

char* join3(char *s1, char *s2)
{
char *result = malloc(strlen(s1)+strlen(s2)+1);
if (result == NULL) exit (1);

strcpy(result, s1);
strcat(result, s2);

return result;
}
